Drug Calculations

Desired Over Have Calculator

Volume to give from the ordered dose and the dose on hand; the basic dose-to-volume check.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

Turn on JavaScript to use this calculator, or open it in the web app.

Formula

(Desired / Have) * Quantity

How it is used

• Volume = desired ÷ have × quantity. Example: 250 mg ordered, 500 mg in 5 mL on hand gives 2.5 mL.
• Put the ordered and available doses in the same unit first (g to mg, mg to mcg).
• Check that the answer is reasonable: many tablets or a very large volume usually means a setup error.

Same formula as the app. Open it in the web app.

Drip cards with a dose ↔ mL/h converter

Related calculators

• Drip Rate (drops/min)
• mcg/kg/min to mL/hr
• Push-Dose Epinephrine
• Weight-Based Dose (mg/kg)

For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your local protocols and medical direction. Not a substitute for clinical judgment.